Acoustical wall covering



C. K. ROOS ET AL ACOUSTICAL WALL COVERING June 23, 1936.y

il'ed July 2o,

l v... A.

Patented June 23, y1936 ACOUSTICAL WALL COVERING Carlisle K. Roos, Wheaton, and George D. King,

Chicago, Ill., assignors to United States Gypsum Company, Chicago, Ill., a corporation of Illinois Application July 20, 1933, Serial No. 681,306

Y 10 Claims.

'I'his invention relates toy improvements in acoustical construction and has .particular relation to acoustical coverings forv walls, ceilings, and the like, all of which are intended to be 5 comprehended within the generic' term "walls".

The use of various types of sound-absorbing materials, including both compressible and porous materials, as acoustical wall coverings, has, of course, been known in the art for many years.

l Such materials have included hair felt, wool felt, mineral wool, fibrous compositions, etc., in the various forms of slabs, matts, sheets, loose materials and the like. In some cases such materials have been surfaced with a porous or perforated l membrane with the object of improving appearance and securing some degree of paintability and cleanability. In such cases it has been the practice to carefully refrain from painting in a manner which would close the pores or perforations in the membrane and thereby render the same impervious to the passage of air and sound Waves through the membrane into direct contact I with the sound-absorbing material behind the same. This precaution has been considered essential in order to avoid destruction or material impairment of the acoustical value of the construction.

In observing this precaution, many of the advantages which may be derived from the use of a surfacing membrane have been lost. The primary function of such membranes is of course, to conceal and enclose the unsightly and unsanitary sound-absorbing material, and to present a `,urface which is less susceptible to dirt accumulation, may be more readily cleaned and is of high light reflectivity. The porous or perforated membranes heretofore used, however, overcome these difliculties only in small part and without entire satisfaction. Y 40 The primary object of the present invention is to provide an arrangement in which the above and other diiliculties and defects` are entirely overcome, without sacrificing the acoustical quality of the construction.

With the above and other objects in view, the invention consists, in general, in the use of a compressible sound-absorbing material as a Wall covering, with a flexible membrane facing which is substantially impervious to the passage of air. It has been found that membranes of various types answering this general description may be used to great advantage in various relations to the compressible sound-absorbing material, certain examples of which are hereinafter disclosed 55 in detail. More specifically, the membrane may be arranged to be in contact with the compressi- 'over the entire surface or at spaced intervals.

Alternatively, the membrane may be spaced from the sound-absorbing material and it may be secured in place by nails or other securing means instead of by adhesives. Both the sound-absorbing material and the membrane may be made of various materials, and a number of examples of' different materials which are suitable'in both cases will be set forth hereinafter.

The invention will be more fully understood by reference to the following detailed description, taken in conjunction with the accompanying drawing forming a part hereof, in which:

Figure 1 is a fragmentary sectional view of an acoustical construction including a wall covering of compressible sound-absorbing material faced with a flexible membrane in contact therewith and adhesively secured thereto over substantially the entire surface thereof;

Fig. 2 is a similar view of a modified construction in which the membrane is in contact with the sound-absorbing material over substantially the entire surface thereof b'ut is adhesively secured thereto at spaced intervals only;

Fig. 3 is a similar view of a modification in which the membrane is spaced from the surface of the sound-absorbing material; and

Fig. 4 is a similar view of a further modification in which the membrane is secured in place in a different manner.

Referring first to Fig. 1 of the drawing, a wall or ceiling-II is shown as having its normally exposed surface covered with a layer of compressible sound-absorbing material I2 which, in turn, is faced with `a flexible membrane I3. The sound-absorbing material I 2 is shown as being held in place .by nails I4, although any other desired type of securing means may be utilized. The membrane I3 is secured to the face ofthe sound-absorbing material I2 by any'suitable adhesive I5, extending in a thin layer over substantially the entire surface of the sound-absorbing material.

or slabs of wool felt are entirely suitable for thisv purpose. Other suitable materials are hair felt, mineral wool, compressible slabs or matts of fibrous composition, sponge rubber mats having connected pores open at the surface, and the like. The membrane I3 may suitably 'consist of paper of various types and qualities. Either coated or uncoated Apaper may be utilized and paper which has been subjected to'any desired type of treatment is likewise suitable. Other suitable examples are wall paper, oil cloth, metal foil, coated fabrics, and asbestos paper which has been painted to render the same substantially impervious to air and water vapor, etc.

It has been found that the membrane does not have to be of any certain composition or possess any particular inherent characteristics such, for example, as would be possessed by a rubber sheeting. The only requirement is. that the membrane be of such thickness according to the material used, and that it be so mounted as to be readily exible, so that sound waves impinging thereon will not be largely reilected. It will be understood, of course, that materials of diierent composition or physical characteristics will require different limits in thickness to be suitable as surfacing membranes. For example, an aluminium foil of .0005" thickness is found to be very satisfactory, a zinc foil .01" has been found not to be satisfactory for absorption of sound at certain frequencies, while a chip paper of even .04" thickness is sufficiently flexible or vibratory to be a practical membrane. It has been found that the exibility of the membrane is apparently the property which determines its suitability. 'There are definite limits of thickness A for each material beyond which the flexibility is not sufficient-to give good results.

From tests which have been conducted'wit various membranes and various compressible absorbents, it is apparent that membranes of the same degree of iiexibility do not necessarily give the best results with all types of absorbents. The degree of resiliency or compressibility of the absorbent, which governs the sound-damping qualities thereof, also governs the desirable limits ot flexibility of the membrane. It appears that the greater the damping qualities of the absorbent; the thicker or stiffer tle membrane may be. It will be understood, however, that such variations determine the effectiveness of the invention only as a-matter of degree and that suitable limits may be readily determined for each combination of materials which it may be desired to utilize. In general, the broad combination of a compressible sound-absorbing material and a flexible surfacing membrane substantially impervious to the passage of air will achieve the fbjects of the invention to a marked degree.

It will be seen that membranes of various materials possessing the desired` characteristics of cleanability, paintability and light reflection may be readily selected, When the membrane is painted or to be painted, the flexibility must be considered and the membrane made suiiciently flexible to start with, so that the addition of successive coats of paint will not unduly decrease such flexibility. It has beenv found, however, that it is not necessary to use a paint of the' socalled flexible type. i

Fig. 2 of the drawing illustrates an arrangement similar to that shown in Fig. 1, except that the membrane I3 is secured to the face of the sound-absorbing material I2 by smaller areas of glue or other adhesive I5. This material may be applied in spots or strips only, rather than overA the entire surface. The distance by which these spots or strips are separated may be varied within any desired limits so long as the membrane is supported at sufficiently close intervals to prevent sagging thereof. This leaves the membrane ceiling or other wall.

- free from the sound-absorbing material over a large part of its area, and, in general, permits the use of a somewhat less flexible membrane than in the ilrst instance, where the continuous layer of adhesive increases the effective stiffness of the membrane to some extent. The use of a flexible glue or other adhesive is not necessary with either type of construction.

The arrangement shown in Fig. 3 differs from the preceding forms in that the membrane I3 is spaced outwardly from the surface of the soundabsorbing material I2. This relationship may be suitably obtained by securing the sound-absorbing material in place by means of furring strips I6 through which nails I'I extend into the The furring strips may be uniformly spaced from the wall surface by spacing blocks I8 or other suitable means if desired. The membrane is shown in this modification as being lglued or otherwise adhesively secured to the outer faces of the furring strips I6, as indicated; at I9. 1

An alternative method of securing the membrane to the furring strips I6 is illustrated in Fig. 4, and consists in the use of outside furring strips 20 overlying the strips I 6 and secured in place by nails 2i extending into the latter. Either the strips I6 or the strips 20, or both, may extend both longitudinally and transversely over any given. area if desired. 'Ihe membrane I3 may be` initially secured in place by glue or adhesive I9 on the surface of the strips I6, although in general this additional method of attachment is not required where the outside furring strips 20 are utilized. A Any other desired means may be utilized for securing the membrane in its desired position.

For example, mechanical means extendingthrough the membrane and the sound-absorbing material into the wall or ceiling will serve to produce the desired ultimate arrangement. In any case, however, rigid attaching means should not be provided at such close intervals that the membrane will be rendered unduly stiff, and, therefore, too reflective of sound. If comparatively close nailing or the like is desirable, a more flexible membrane should be selected in order to avoid excessive reduction in its flexibility.

The high sound-absorbing eiiciency which has been found to be obtained with the above-described arrangements and various other modifications, is believed to be due to the additive effect of three agencies. When sound waves impinge upon the membrane, the latter is vibrated and transmits sound to the absorbing material behind the same, which disspates it in the same manner as such absorbents do ordinarily. It should be understood, however, that this transmission, of

sound by the membrane is not by actual passagev of sound waves through the membrane, as would be the case if it were porous or perforated, but byY vibratory movement set up in the membrane itself by the sound waves, in which there is little energy returned by reection from the membrane. A large part of the energy is transformed into new but similar waves which are set up behind the membrane and which aredirectly absorbed by the sound-absorbing material. This absorption is ordinarily explained as being dueto the sound waves penetrating into the interstices of the material where the energy is dissipated by conversion into heat.

The second' factor contributing to the total ab- .sorption of the construction is that resulting from the compression of the combination of confined air and absorbing material. The absorbing material being compressible, the membrane will ride back and forth on the surface thereof, if arranged in contact therewith, as on an air cushion; in cases where the membrane is spaced outwardly from the surface of the absorbing material, there is a definite air cushion and the compression of the absorbing material is transmitted therethrough from the membrane. In other words, the air-felt column behind the vibrating membrane may be regarded as somewhat inelastically vWith such sound-absorbing materials, the combination, including the membrane, gives a decidedly increased sound absorption over that of the 'sound-absorbent material alone. This feature, obviously, is of considerable importance.

As above indicated, the use of a compressible sound-absorbing wall covering in combination with a flexible membrane, substantially impervious to the passage of air, extending over the surface thereof, has been found to produce highly advantageous results from an acoustical standpoint, and such combination is accordingly broadly claimed herein. t

In referring to the membranes as being subv stantially impervious to the passage of air, it-will be understood that a limitation to completely impervious and non-porous products is not intended.

For example, paper and similar products might not be considered to be absolutely air-tight, but, to all intents and purposes, they are substantially impervious to the passage of air, and therefore fully comply with the requirements of the present invention.

The use of substantially impervious membranes produces a further marked advantage in that they prevent the material of the sound-absorbent base from sifting or dusting through the membrane covering onto the objects in the room. This objectionable result is obtained to a great extent when perforated membranes or the like are used, particularly when the building structure is subject to vibrations of any kind. Painted membranes are highly-advantageous because they are sub" stantially impervious to water vapor as well as to air, and therefore dimensional changes due to changes in humidity are greatly decreased, with a corresponding decrease in the tendency of the membranes to sag.

Other terms used in the foregoing description and appended claims will be readily understood from the context. The 4term wall, as above indicated, is used generically to designate both walls and ceilings as well as any other partition or surface bounding a room or other enclosure. Reference to the 'face of such a wall or of a covering therefor designates the surface thereof which faces inwardly toward the room, as distinguished from the rear surface. The term covering does not necessarily imply the extension of the covering layer over the entire surface of a wall, but may refer to only a portion of such wall surface.

4having a normally exposed surface, a covering While only certain specific embodiments of the invention have been shown and described in detail herein, it will be readily .understood by those skilled in the art that various changes and modifications in the details of construction and ar- .5 rangement of parts may be made without departing from the spirit and scope of the invention, as set forth in the appended claims. f

What is claimed as new and is desired to secure by Letters Patent, therefore, is:

1. An acoustical construction comprising a wall having a normally exposed surface a covering forsaid surface of compressible, sound-absorbent material, and a flexible membrane sub. stantially impervious to the passage of air exl5 tending over the face of said covering and in contact therewith over substantially the entire surface thereof.

2. An acoustical construction comprising a wall having a normally exposed surface, a cov- 20 ering for said surface of compressible, sound-absorbent material, and a flexible membrane substantially impervious to the passage of air extending over the face of said covering and adhesively secured thereto over substantially the entire sur- 25 face thereof.

3. An acoustical construction comprising a wall having a normally exposed surface, a covering for -said surface of compressible, sound-absorbent material, and a flexible membrane substantially 30 impervious to the passage of air extending over the face of said covering and adhesively secured thereto at spaced intervals. y

4. An acoustical construction comprising a wa11` having a normally exposed suiface, a covering 35 for said surface of corr bressible, sound-absorbent material, and a exible membrane substantially impervious to the passage of air extending over the face of said covering and in contact therewith over substantially the entire surface thereof and 40 adhesively secured thereto at spaced intervals.

5. An acoustical construction for controlling the reverberation within an enclosed space which comprises surfaces bounding said space, some, at least, of said surfaces being lined with compressible coherent vporous sound-absorbing material, and a thin flexible membrane substantially impervious to the passage of air covering said material, being in contact vtherewith and adhering thereto. 50

6. An acoustical construction for controlling the reverberation within an enclosed space which comprises surfaces bounding said space, some, at least, of said surfaces being lined with compressible coherent porous sound-absorbing material, 5* and a thin flexible membrane substantially impervious to the passage of air-covering said material, being in contact therewith and adhering thereto at spaced intervals.

7. An acoustical construction comprising a wall 60 having a normally exposed surface, a covering for said surface of compressible, sound-absorbent material located in contact with .said surface, and a flexible membrane substantially impervious to the passage of air extending over the face of said covering and inv contactl therewith over substantially the entire surface thereof.4

8. An aoustical construction comprising a wall for said surface of compressible, sound-absorbent",

face thereof. 75

9. An acoustical construction comprising a wall having a normally exposed surface, a covering for said surface of compressible, sound-absorbent material, and an impervious metal foil membrane extending over the face of said covering and in contact therewith over substantially the entire surface thereof.

10. An acoustical construction comprising a wall having a normally exposed surface, a covering for said surface of compressible, sound-absorbent material, and a coated fabric substantially impervious to the passage of air extending over the face of said covering and in contact therewith over substantially the entire surface 

